Method of and apparatus for grinding gears



Nov. 10, 1931. H. E. TAYLOR METHOD OF AND APPARATUS FOR GRINDING GEARS Filed April 13, 192G 6 Sheets-Sheet l INVENTOR I Hrfieri E Taylor BY v ATTORNEY Nov. 10, 1931. H. E. TAYLOR 1,830,971

METHOD OF AND APPARATUS FOR GRINDING GEARS Filed April 13, 1926 6 Sheets-Sheet 2 INVENTOR ATTORNE7 Nov. 10, 1931 H. E. TAYLOR 1,830,971

METHOD OF AND APPARATUS FOR GRINDINCT GEARS Filed April 13, 1926 6 Sheets-Sheet 3 l l' I 6 t? 1m, FHA 72 E 9 73 fi -y gh L INVENTOR flerberziifml ATTORNEY Nov. 10, 1931. v H. E TAYLOR 1,330,971

METHOD OF AND APPARATUS FOR GRINDING GEARS Filed April 13, 1926 6 Sheets-Sheet 4 INVENTOR emerilifilylor ATTORNEY Nov. 10, 1931. H. E. TAYLOR- 1,830,971

METHOD OF AND APPARATUS FOR GRINDING GEARS Filed April 13, 1926 6 Sheets-Sheet 5 INVENTOR Jgg'bez'ZE Taylor Nov. 10, 1931'. H. E'. TAYLOR 1,830,971

METHODOF AND APPARATUS FOR GRINDING GEARS Filed April 13, 1926 6 Sheets-Sheet 6 INVENTOR ATTORW Patented Nov. 10, 1931,

nurse rates Praia hddml HERBERT EDGAR TAYLOR, 0F COVENTRY, ENGLAND, ASSIGNOR T0 GLEASON WORKS, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW' YORK METHOD OF AND APPARATUS FOR GRINDING- GEARS Application filed April 13, 1926. Serial No. 101,776.

The present invention relates to a method and apparatus for finishing longitudinally curved tooth gears by grinding.

The primary object of this invention is to provide a method and apparatus for finishing the surfaces of gear teeth by grinding, after they had been cut and hardened, where- 'by they will have accurately finished and smooth running tooth surfaces.

A further object of the invention is to provide mechanism which will grind the tooth surfaces to the desired finish in a rapid and eificient manner.

A still further object of the invention is to provide apparatus for grinding longitudinally curved tooth gears which will be simple in operation and inexpensive to construct.

Other objects of the invention will be apparent hereinafter from the specification and from the recitation of the accompanying claims. p

In the drawings, I have illustrated'certain preferred embodiments of my invention. It will be understood, however, that it is not; intended to limit the invention to the particular embodiments shown, but that the invention is capable of further modification within its scope and the limits of the appended claims.

In the drawings:

Figs. 1 to 1 inclusive are diagrammatic views, showing the preferred form of tool, employed in practising my invention, and illustrating by way of comparison the advantages of this form;

Figs. 5 and 6 are diagrammatic views illustrating the manner of employing the tool in grinding a gear whose teeth are curved longitudinally in the form of a circular are or a gear which is conjugate to such a longitudinally curved tooth gear;

Figs. 7 and 8 are a side elevation and a plan view, respectively, of one form of grinding machine constructed according to this invention;

Fig. 9 is a fragmentary side elevation, showing the means for imparting a relative rolling motion between the grinding wheel and the gear to be ground in the machine of Figs. 7 and 8;

Figs. 10 and 11 are a side elevation and plan View, respectively, of a somewhat modified form of machine;

Fig. 12 is a vertical sectional View, showing the tool mounting employed in grinding 55 gears whose teeth are curved longitudinally on other than circular arcs, or gears conjugate to such curved tooth gears;

Fig. 13 is a section on the line iii-13 of Fig. 12;

Fig. 14 is a' diagrammatic view illustrating the method of positioning the grinding wheel for grinding a gear Whose teeth are longitudinally of involute curvature;

Figs. 15 and 16 are a side elevation and a plan view, respectively, showing one form of dressing mechanism which may be employed with apparatus constructed accord ing to this invention to dress the grinding wheel;

Figure 17 is a section on the line 1717 of Figure 7; i

Figure 18 is a detail view of parts ofthe generating mechanism shown in Figure 9;

Figures 19 and 20 are a transverse sectional View and a longitudinal sectional view, respectively, of the dresser actuating mechanisgn, shown generally in Figures 15 and 16; an

Figure 21 is a partial rear elevation of the machine shown in Figures 10 and 11.

It is customary to grind the tooth surfaces of a gear after the same has been cut and heat-treated in order to remove from the finished tooth surfaces any imperfection due to the hardening or heat-treating process. The present invention is intended principally for finishing the tooth surfaces of curved tooth tapered gears, though it may be applied also to the grinding of curved tooth spur gears or curved tooth gears of other types.

In general, the present invention consists in employing a rotary grinding wheel and imparting to this wheel a rotary movement on its axi while simultaneously moving it, preferably reciprocating it, in a curved path across the face of the gear being ground. If the tooth profiles of the gear to be ground have been generated, an additional generating or rolling movement will be imparted, si-

multaneously with the grinding movement, between the wheel and gear.

Curved tooth gears are ordinarily produced in a cutting operation with a rotary annular face mill. These tools are provided with a plurality of annularly arranged cutting blades, each of which is relieved rearwardly of its cutting edge or edges to provide the required clearance during cutting. Gears cut with such tools may be ground with a grinding wheel of similar structure, that is, with a rotary annular grinding wheel. The grinding surface of such a wheel, however, is uninterrupted and cannot be relieved. Difficulty is sometimes experienced, therefore, in grinding curved tooth gears, with such wheels, in maintaining suflicient clearance between the grinding surfaces of the wheel and the tooth surfaces being ground. Where the required clearance cannot be secured there is always the possibility that the contacting surfaces of wheel and gear will become overheated and serious damage to the gear tooth surfaces may result. My invention provides a method of grindng curved tooth gears in which sufficient clearance be tween the sides of the teeth and the operating surfaces of thegrinding wheel may be always secured and through which burning of the gear tooth surfaces is entirely prevented.

As has already been stated, the present invention includes the use of a rotary grinding wheel which is simultaneously rotated on its axis and preferably reciprocated in a curved path across the face of the gear being ground. The wheel employed will have a profile conjugate to the profile of the gear tooth being ground. In grinding a generated gear the profile of the wheel surfaceswill be that of the basic-gear with which during the generating motion the gear theoretically rolls.

In its preferred form, the wheel employed with my invention will be of dished shape, since I have found that with this form of wheel I can always obtain uniform side clearance. The use of such a wheel. moreover, will give increased strength and prolonged life.

The advantages of this form of wheel are illustrated diagrammatically in Figs. 1 to 4 inclusive where the preferred type of wheel 10 is compared with a disc grinding wheel 11. The dotted lines 12 and 13 in Figs. 1 and 3 represent respectively planes tangent to the pitch and root surfaces of the gear to be ground. while the sections of Figs. 2 and 4 are sections in the plane 12, tangent to the pitch surface of this gear or in any plane parallel thereto. The wheel 11 is provided with operating surfaces 14 and 14 and the wheel 10 with operating surfaces 16 and 16'. The operating surfaces in each case have a profile conjugate to the profile of the teeth to be ground. The pitch lines of the tooth sides to be ground are indicated by the lines side 17 This side 14' is curved about a center 15 which lies on the opposite side of the tooth space from the center 19 of tooth curvature and ordinarily the clearance between this side 14' and the tooth side 18 will be too great. The wheel 11., therefore, clears too much on one side and not enough on the other. Its structure, therefore, is undersirable. The wheel 10 on the other hand is of general crescent shape in the tangent plane and its operating surfaces 16 and 16 will haye a desirable amount of clearance with reference to the sides of the teeth each operates upon. The operating surfaces of the wheel 10 are respectively convex and concave conforming in this respect to the sides of the tooth space so that the size of the wheel and its area of contact can be readily controlled. The wheel 10,

moreover, can be made larger than the wheel 11. without interfering with the tooth sides.

This latter quality makes for strength and long life.

In the form illustrated, the operating surfaces of the wheel 10 are parts of conical surfaces whose apexes lie on the same side of a plane drawn perpendicular to the axis'20 of the wheel at its tip surface 21. It will be understood, however, that I do not desire to limit my invention to the use of conical operating surfaces, but that the operating surfaces may be of any desired or suitable geometric form.

In grinding gears whose teeth are curved longitudinally on circular arcs or in grinding gears conjugate to such longitudinally curved tooth gears, the grinding wheel 10 will preferably be so. positioned that its axis 20 passes through the. center 19 of tooth curvature. The relationship between the grinding wheel 10 and the rotary face mill 22 employed in cutting the gears 23 to be ground is illustrated in Figs. 5 and 6. The profile of the grinding wheel is the same as the profile of the cutter, and the grinding wheel will be moved in the same path as that in which the blades of the cutter 22 moved during cutting. The grinding wheel will be positioned with its axis passing through the center 24 of the cutter which is the center of tooth curvature and will be rotated on its axis while be ing simultaneously swung about the center 24.

The structure of the grinding wheel is capable of modification within practical limits. Preferably the wheel will be of such form that the points 25 and 26 of intersection of normals 28 and 29 with the tool axis 20 will be at the same relati've distances from the center of tooth curvature 19, as the centers '30 and. 31 about which the grinding wheel operating surfaces arecurved in the tangent plane are from the center ofiooth curvature 19. This construction insures of uniform s de clearance on both sides of the grinding wheel.

One form of machine suitable for practising this invention is illustrated in Figs. 7 and 8. Here the grinding wheel 10 is mounted upon a tool spindle 35 which is journaled in suitable hearings in a member 36 which is mounted upon the inclined. surface of a carrier 37 which is mounted for lateral adjustment in guides 38 formed on the cradle or carrier 39 oscillatably mounted on the frame 40 of the machine. The grinding wheel is rotated on its axis and simultaneously therewith oscillated across the face of the gear 23 which is to be ground. For rotating the grinding wheel, a motor 41 is provided. This motor drives the grinding wheel through the bevel gearing 1-2. one member of which has a splined connection with the tool spindle 35. The reciprocatory or oscillatory motion of the grinding whe l is derived from a second motor 43 which is secured to the frame of the machine and which actuates through a worm 4iand a worm wheel 45 a crank member 46 which is journaled in suitable bearings 47 and 48 provided on the frame. This crank n1e1nber46 is connected by the connecting rod 49 with asleeve 50 within which the drive spindle 51 is housed. By means of the crank and connecting rod the grinding wheel is oscillated about the axis of the drive spindle. To prevent vibration, a fly wheel 52 may be provided which is mounted on the bearing stud 53 of the crank 16.

\Vhere generated gears are to be ground' it is necessary to impart in addition to the rotary and oscillatory movements of the wheel. a relative rolling movement between the wheel and gear. This rolling movement may be accomplished through any suitable form of mechanism. In the machine shown, the generating motion is effected from a motor 54 which is mounted along side the motor ll and which actuates through a worm and a worm wheel 56 9) a crank member 57 which is connected by the connecting rod 58 with a spur gear segment 59 rotatably mounted on the frame of the machine. The .pur gear segment59 meshes with an internal segment 60 which is secured to the cradle or carrier 39 on which the grinding wheel is mounted. This cradle -or carrier 39 oscillates about. a bearing 62 (Fig. 8) whose center is on the axis of the basic crown gear or other basic gear with which the gear being ground rolls, theoretically. during the grinding op eration. The cradle or carrier 39is guided during its oscillatory movement by means of ways which engage the guide 63 provided on I the frame of the machine. To the cradle 39 is secured a gear segment 64 (see also Fig. 18) which meshes with a bevel gear segment 65 which is secured to the blank or gear spindle 66. Actuation of the motor 54 will cause the segment 59 to oscillate the segment 60 through the crank 57 and connecting rod 58. The oscillation of the segment 60 will impart an oscillatory movement to the cradle or carrier 39 and simultaneously therewith an oscillatory movement to the blank or gear spindle. Through the combined movements of cradle and blank spindle a relative rolling movement is imparted between grinding wheel and blank during grinding. During engagement with the'wheel, the tooth. sides of the gear. roll in one direction or the other on the surfaces of the grinding wheel. When the grinding wheel is out of engagement with the gear. the gear is indexed.

The blank carrier 68 may be adjusted on the upright 69 formed on the frame 40 to position the gear 23 to be ground at any desired angle and bolts 70 which engage in T-slots 71 in the carrier 68 may be utilized to secure the gear in the desired position. The grinding wheel may be adjusted so that it may grind gears of different sizes and different spiral angles by adjustment of the carrier 37 in the guides 38, by adjustment I of the member 36upon the carrier 37, and

by rotation of the worm 7 2 and worm wheel 73 (Figs. 9 and 12) which latter adjustment alters the position of the wheel relative to.

the stroke of the connecting rod 49. Two

carriers 37 and two guide portions 38 may be provided on the machine so as to assist in readily positioning the wheel for'grinding' gears of opposite hand.

In themachine shown, the grinding wheel 9 will rotate on its axis and simultaneously be reciprocated in a curved path across the face ferred to will be imparted to the blank After the 'sides of one tooth space have been finished, the blank will be indexed to the next tooth space.

The indexing mechanism 74: employed may be of any suitable character and forms no part of the present invention.

in Figs. 10, 11 and 21 I have illustrated a somewhat modified form of machine. The means for imparting to the grinding wheel its rotary and oscillatory movement is the same as in the machine just described. The generating or rolling motion, however, is obtained through a differentarrangement of mechanism. This mechanism includes a motor 7 5 mounted upon an upright 7 6 and operatively connected with a drive shaft 77 to which is fastened a worm 78 which meshes with a Worm wheel 7 91113011 a transverse shaft 80. The shaft 80 drives through the bevel lid gearing 81, the telescoping shaft 82, the bevel gearing 83, the shaft 84, the worm -and the worm wheel 86, the blank or gear spindle 87 to thereby impart to the gear 88 to be ground a rotary movement on its axis. The shaft 80 is connected through change gears 90 with a shaft 91 which carries a worm 92 which meshes with a worm wheel segment 93 which is secured to the cradle or carrier 94, which, as in the previous embodiment is oscillatable about an axis 95 representing the axis,of the gear with which during the generating operation the gear being ground is rolled. For indexing the blank any suitable type of indexing mechanism, indicated generally at 96, may be provided. The blank and .wheel adjustments are the same as already described.

In thev machines described, a pump 97 is provided for pumping the cooling fluid from a reservoir in the base of the machine through a conduit 98 to the vicinity of the grinding operation. This pump is actuated by a pulley 99 driven by a pulley 100 secured to the worm shaft 44. The coolant after use falls in the basin 101 and returns to the reservoir through the pipe 102.

Where it is desired to grind gears, the lo ngitudinal curvature of Whose teeth is of other than circular arc form, a tool drive such as illustrated in Figs. 12 and 13 maybe employed. In this construction, means is provided for altering the path of movement of the wheel so that it will conform to the curvature of the teeth to be ground. This means includes a cam of suitable form which is secured to-the drive spindle housing 111 and which engages with rollers 112 and 113 which are mounted on the frame. As the grinding wheel oscillates across the face of the blank, therefore, it will be moved toward and from its axis of oscillation, the axis of the drive shaft 51, to thus desribe'other than a circular arc across the face of the blank. To insure constant engagement of the rollers and cam, one of '.the'.rollers 112 may be carried on a sleeve 114 which is slidably mounted in a recess in the frame and which is actuated by the coil spring 115 constantly into engage: ment with the cam. The embodiment shown is constructed for grinding curved tooth gears where the basic member, as the crown gear 116 has teeth 117 which are'of involute curvature lengthwise. In grinding such gears, the tool axis 2 0 will be adjusted initially so that the tool oscillates about the point .118 lying on the base circle 119 from which derived.

the longitudinal curvature of the teeth. is

The invention is applicable to the grinding of other types of longitudinally curved tooth gears also and by substitution of a proper form of cam thedesired tool movement can be obtained. i

To maintain the proper grinding profile,

' the grinding wheel should be periodically dressed. This may be'done by hand or automatically. One form of dressing-mechanism is shown in Figs. 15, 16, 19, and 20. This dressing mechanism is mounted on a bracket 120 which is secured to the blank head. The mechanism includes a pair of diamonds 121 and 122'which are mounted on reciprocable slides 123'and 124. The slides are reciprocated by means of cams 125 and 126 which are provided with helical grooves of opposite hand and which engage pins. 145 secured to the slides. The cams are driven from a single bevel gear 127 through individual bevel pinions 128 and 129 which are keyed to the shafts 130 and 131 upon which 'the cams are mounted. 7 Rotation of the shafts 130 and a 131, as is obvious, will cause the dressing diamonds to be moved back and forth across the operating surfaces of the grinding wheel to maintain the same in proper grinding posi- 'tion. In the embodimentillustrated, a motor 132 is shown employed for actuating the diamonds. This motor which may be periodically started through any suitable form of electrical timing device or any other suitable mechanism, drives the bevel gear 127 throughthe shaft 134, the worm 135 and the worm wheel 136 which is mounted-on the shaft 137 to which the bevel gear 127 is keyed. The dressing mechanism is so positioned that the grinding wheel may be dressed when it has been swung clear of the gear being ground. The dressing diamonds can be adjusted to dress wheels of different pressure angle by moving the slide carriers 138 and 139 on the bracket 120. These slide carriers can be secured in any adjusted position by means of bolts 140 which engage in circular slots 141 formed on the bracket 120. The diamonds can be adjusted to take up for wear by means of knurled nuts 142.

- While I have illustrated certain preferred embodiments of my invention, it will be understood that this invention is capable of further modification within the limits of the disclosure and the scope of the appended claims and that this application is intended to cover any variations, uses, or adaptations of my invention, following,'in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practise in the gear art and as may be applied to the ess'ential'features hereinbefore set forth and as fall within the limits of the accompanying claims.

Having thus described my I claim is:

1. The method of grinding the side tooth surfaces bf a longitudinally curved tooth gear which consists in rotating a grinding wheel on its axis while moving it in a longitudinally curved path across the face of the gear to be ground and simultaneously imparting a relainvention, what tive rolling motion between said wheel and ear.

g 2. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in rotating a grinding wheel on its axis and simultaneously reciprocating it in a longitudinally curved path across the face of the gear to be ground. I

3. The method of grinding the side tooth surfaces of a longitudinally curved tooth car which consists in rotating a grinding w eel on its axis while moving it in a longitudinally curved path across the face of the gear to be ground and simultaneously imparting an additional relative motion between the wheel and gear for grinding the tooth profiles.

4. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in rotating a grinding wheel on its axis while reciprocating it in a longitudinally curved path across the face of the gear to be ground and simultaneouslyimparting an additional relative movement between the wheel and gear for grinding the tooth profiles.

5. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in rotating a grinding wheel on its axis and simultaneously imparting to it an oscillatory movement about another axis to move the wheel across the face of the gear to be ground. v

6. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in rotating a grinding Wheel on its axis and simultaneously oscillating it about another axis to move the wheel in a lon gitudinally curved path across the face of the gear, and simultaneously imparting an additional relative movement between the wheel and gear for grinding the tooth profiles.

7. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in reciprocating in a longitudinally curved path across the face of the gear to be ground, a grinding-tool having an operating portion of general crescent shape in a section tangent to the pitch surface of the gear to be ground.

8. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in reciprocating in a longitudinally curved path across the face of the gear to be ground, a grindingv tool having an operating portion of general crescent shape in a section tangent to the pitch surface of the gear and simultaneously imparting a relative rolling motion between said tool and gear.

9. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in selecting a dished grinding wheel, having active grinding surfaces which are portions of the outside and inside surfaces of the wheel, and positioning said wheel relative to the gear to be ground so that its axis is inclined at an aoute angle to a plane tangent ta the pitch surface of the gear to be ground, and imparting to the wheel the rotary motion on its axis and simultaneously moving it in a longitudinally curved path across the face of the gear to be ground.

10. The method of grinding the side tooth surfaces of a longitudinally curved tooth gpar which consists in selecting a dished grin 'ng wheel, having active grinding surfaces are portions of the outside and inside surfaces of the wheel, and positioning said wheel relative to the gear to be ground so that itswhich are portions of the inside and outside surfaces of the wheel, and positioning said wheel'relae tive to the gear to be ground so that its axis is inclined at an acute angle to a plane tan-.

gent to the pitch surface of the gear, and rotatin the wheel on its axis while simultaneous y reciprocating it in a longitudinally curved path across the face of the gear.

12. The method of grinding the side tooth i surfaces of a longitudinally curved tooth ear which consists in selecting a dished grin ing wheel having active grinding surfaces which are portiops of the outside and inside surfaces of the wheel, and positioning said wheel relative to the gear to be ground so that its axis is inclinedat an acute angle to a plane tangent to the pitch surface of the gear, rotating the wheel on its axis and simultaneously reciprocating it in a longitudinally curved path across the face of the gear to be ground while imparting an additional relative movement between the wheel and files of the gear teeth.

13. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in selecting a dished grinding wheel having an active grinding surface which is a portion of the concave surface of said wheel rotating the wheel on its axis and simultaneously reciprocating it in a longitudinally curved path across the face of the gear to be ground.

14. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in selecting a dished grinding wheel having an active grinding surface which is a portion of the concave surface of said wheel, rotating the wheel on its axis while reciprocating it in a longitudinally gear to grind the pro ,said wheel, rotating the wheel on its axis while reciprocating it in a longitudinally curved path across the face of the gear to be ground and simultaneously imparting an additional relative motion between the wheel and gear for grinding the tooth profiles.

16. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in employing a dished grinding wheel having active grinding surfaces which are portionsof the inside and outside surfaces of the wheel, positioning said wheel so that its axis is inclined to a plane tangent to the pitch surface of the, gear to be ground,

rotating said wheel on its axis and simultaneously oscillating said wheel about another axis to move the tool in a longitudinally curved path across the face of the blank.

17. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in employing a dished grinding wheel, having active grinding surfaces which are portions of the inside and outside surfaces of the wheel, positioning said wheel so that its axis is inclined to a plane tangent to the pitch surface of the gear to be ground, rotating said wheel onits axis while oscillating it about another axis to move the tool in a longitudinally curved path across the face of the blank and simultaneously imparting a relative rolling motion between said wheel and gear.

18. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in employing a dished grinding wheel having active grinding surfaces which are portions of the outside and inside surfaces of the wheel, positioning said wheel so that its axis is inclined to a plane tangent to the pitch surface of the gear to be ground, rotaing said wheel on its axis while simultaneously oscillating said wheel about another axis to move the wheel in a longitudinally curved path across the face of the gear, and simultaneously imparting an additional relative movement between the wheel and gear for grinding the tooth profiles.

19. The method of grinding the longitudinally convex side surfaces of a longitudinally curved tooth gear which consists in employing a dished grinding wheel, having an active grinding surface which is a portion of the concave surface of the wheel, positioning said wheel so that its axis is inclined at an acute angle to a plane tangent to the pitch surface of the gear to be ground, rotating said wheel on its axis and simultaneously oscillating said wheel about another axis to move the Wheel in a longitudinally curved path across the face of the gear.

20. The method of grinding the longitudinally convex side surfaces of a longitudinally curved tooth gear which consists in employing a dished grinding wheel, having an active grinding surface which is a portion of the concave surface of the wheel, positioning said wheel so that its axis is inclined at an acute angle to a plane tangent to the pitch surface of the gear to be ground, rotating said wheel on its axis while oscillating it about another axis to move the wheel in a longitudinally curved path across the face of the gear and simultaneously imparting a relative rolling motion between said wheel and gear.

21. The method of grinding the longitudinally convex sides of the teeth of a longitudinally curved tooth gear which consists in employing a dished grinding wheel having an active grinding surface which is a portion of the concave surface of the wheel, and positioning said wheel so that its axis is inclined at an acute angle to a plane tangent to the pitch surface of the gear to be ground, rotating said wheel on its axis and simultaneously oscillating said wheel about another axis to move the wheel in a longitudinally curved path across the face of the gear and simultaneously imparting an additional relative movement between the wheel and gear for grinding the tooth profiles.

22. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in rotating a grinding wheel on its axis while imparting to the wheel an oscillatory motion on a separate axis and simultaneously therewith imparting a relative movement between said wheel and the gear to be ground toward and away from said axis of oscillation to cause the wheel to trace a path other than a circular arc across the face of the gear.

23. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in rotating a grinding wheel on its axis while imparting to the wheel an oscillatory motion on a separate axis and simultaneously therewith imparting a rela tive movement between said wheel and the gear to be ground toward and away from said axis of oscillation to cause the wheel totrace a path other than a circulanarc across the face of the gear to be ground and simultaneously imparting a relative rolling motion between said wheel and gear.

24. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in positioning a dished grinding wheel, having active grinding surfaces which are portions of the inside and outside surfaces of said wheel, so that its axis is inclined at an acute angle to a plane tangent to imparting to the wheel an oscillatory motion on a separate axis and simultaneously therewith imparting a relative movement between said wheel and the gear to be ground toward and away from ,said' axis of oscillation to cause the wheel to move in apath other than a circular arc across the face of the gear.

25. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in positioning a dished grinding. wheel, haying active grinding surfaces which are portions of the inside and outside surfaces of said wheel, so that its axis is inclined at an acute angle to a plane tangent to the pitch surfaceof the gear to be ground, rotating said grin ding wheel on its axis, while imparting to the wheel an oscillatory motion on a separate axis and simultaneously therewith imparting. a relative movement between said wheel and the gear to be ground toward and away from said axis of' oscillation to cause the wheel to move in a path other than a circular arc across the face of the gear and simultaneously imparting a relative rolling motion between said wheel and gear.

26. The method of grinding the side tooth surfaces of a longitudinally curvedtooth gear which consists in positioning a dished grinding wheel, having an .active grinding surface which isa portlon of the concave surface of said wheel, so that its axis is inclined at an acute angle to a plane tangent to the itch surface of the gear to be ground, rotatmg said wheel on its axis, while imparting to the wheel an oscillatory motion on a separate axis and simultaneously therewith imparting a relative movement between said wheel and the gear to be ground toward and away from said axis ofoscillation to cause the wheel to move'in-a path other than a,

circular arc across the face of the gear.

27. The method of grinding theside tooth surfaces of a longitudinallycurved tooth gear which consists in positioning a dished grinding wheel, havingan active grinding surface which is aportion of the concave surface of said wheel, so that its axis-is inchned at an acute angle to a plane tangent to the pitch surface of the gear tobe ground,

rotating said wheel on its axis, While imparting to the wheel an oscillatory motion on a separate axis and simultaneouslytherewith imparting a relative movement between said wheel and the gear to be ground toward and -awayfrom said axis. ofoscillationto cause the wheel tomov'e in a path other than a cir-v cular arc across the face of the gear and simultaneously. imparting a relative rolling motion between said wheel and gear. v '28. The methodof grinding the side tooth gear which consists in employing a dished at its tip, positioning. said wheel so that its axis is inclined to a plane tangent to the pitch surface of the gear to be ground and rotating said wheel on its axis while reciproeating it ina longitudinally curved path across the face of the gear being ground.

29. The method of grinding the side tooth surfaces of a longitudinall Y curved tooth gear which consists in emp oying a dished grinding wheel, having conical grinding surfaces whose a exes lie on the same side of a plane perpen icular to'the axis of the wheel at its tip, positioning said Wheel so'that its axis is inclined to a plane tangent to the pitch surface of the gear to. be ground, rotating said wheel on its axis, and reciprocatingsaid wheel in a longitudinally curved path across the face of the gear being ground while im parting a relative rolling motion between said wheel and gear. 30. T hemethod of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in employing a dished grinding wheel, havingconical grinding surfaces whose apexes lie on the same side of'a plane perpendicular to the axis of the wheel at ts tip, positioning said wheel so that its axls is inclined to aplane tangent to the pitch surface of the gear to be ground, rotatmg said wheel 011 its axis and simultaneously oscillating said wheel about another axis to move the wheel in a longitudinally curved path across the face of the gear.

31. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear whic consists in employing a dished grinding w faces whose apexes lie on the, same side of a plane perpendicular to the axis of the wheel at ts tip, positioning said wheel so that its axis is inclined at an acute angle to a plane tangent to the pitchsurface of the gear to be ground, rotating said wheel on its axis and simultaneously oscillating said wheel about another axis to move the wheel in a longitudinally curved path across the face of the gear, and simultaneously producing an addimovement to the grinding wheel and means (path across the eel, having conical grinding suri pp grinding wheel, means for imparting a rotary for simultaneously moving the wheel bodily ina longitudinally curved faceojf the gear being groun W 3 '33.,"In a machine for igrinding' longitudij nallycurved tooth gears, a blank support, a

' ,grin'dipg wheel, means for imparting arotary v I movement to the grinding wheel,;means for surfaces of a long'tudinally curved tooth simultaneously moving the wheel bodil ina of the gear being ground and means for simultaneously imparting a relative rolling motion between said wheel and gear.

34. In a machine for grinding longitudinally curved tooth gears, a blank support, a grinding wheel, means for imparting a rotary movement to the grinding wheel, means for simultaneously moving the wheel bodily in a longitudinally curved path across the face of-the gear being ground and means for simultaneously imparting an additional relative motion between the wheel and gear for grinding the tooth profiles.

In a machine for grinding longitudinally curved tooth gears, a blank support, a grinding wheel, means for rotating the grinding wheel on its axis and means for simultaneously reciprocating the wheel bod ily in a longitudinally curved path across the face of the gear to be ground.

36. In a machine for grinding longitudinally curved tooth gears, a blank support, a grinding wheel, means for rotating the grinding wheel on its axis, means for simultaneously reciprocating the wheel bodily in a longitudinally curved path across the face of the gear to be ground, and means for simultaneously imparting a relative rolling motion between said wheel and gear.

37. In a machine for grinding longitudinally curved tooth gears, a blank support, a grinding wheel, means for rotating the grinding wheel on its axis, means for simultaneously reciprocating the wheel bodily in a longitudinally curved path across the face of the gear to be ground, and means for simultaneously imparting an additional relative motion between the wheel and grinding the tooth profiles.

38. In a machine for grinding longitudinally curved tooth gears, a blank support, an oscillatable wheel carrier. a ,wheel spindle journaled therein, a grinding wheel secured to said spindle, means for oscillating the wheel carrier to move the wheel in a longitudinally curved path across the face of the gear and means for simultaneously rotating the wheel on its axis.

39. In a machine for grinding longitudinally curved tooth gears, a blank support, an oscillatable wheel carrier, a wheel'spindle journaled therein, a grinding wheel mounted thereon, means for oscillating thewhe'elgcarricr to move vthe wheel in longitudinally gear for,

' ,tool support, a grlnding wheel, having an curved path across the face of the gear, means" for simultaneously rotating the wheel spindle wheel, journaled in said tool supports, with its axis inclined at an acute angle to a plane tangent to the pitch surface of the gear to be ground, means for rotating the grinding wheel on its axis and means for simultaneously reciprocating said grinding wheel bodily in a longitudinally curved path across the face of the gear to be ground.

41. In a machine for grinding longitudinally curved tooth gears, a blank support, a tool support, a dished grinding wheel, having active grinding surfaces which are portions of the inside and outside surfaces of the wheel, journaled in said tool supports, with its axis inclined at an acute angle to a plane tangent to the pitch surface of the gear to be ground, means for rotating the grinding wheel on its axis, means for simultaneously reciprocating said grinding wheel bodily in a longitudinally curved path across the face of the gear to be ground and means for simultaneously imparting a relative rolling motion between said wheel and gear. I

42. In a machine for grinding longitudinally curved tooth gears, a gear support, a tool support, ,a grinding wheel mounted on said support,"means for rotating the grinding wheel on its axis, means for simultaneously imparting to the grinding wheel an on its axis, and means.for-simultaneously imparting an additional relative movement between the wheel carrier-and:blanksupport for grinding the tooth profiles. I 1

40. Ina machine for grinding longitudinally curved toothgears,-ablank supportfa tool support, a dishedgrinding-wheel; having active grinding-surfaces which are-portions of the inside and outside surfaces ofthe oscillatory movement about a separate axis, and means for simultaneously imparting a relative movement between said wheel and the gear to be ground toward and from said axis of oscillation to cause the wheel to move in a path other than a circular arc across the face of the gear.

43. In a machine for grinding longitudinally curved tooth gears, a gear support, a

operating portion of general crescent shape in a plane tangent to the pitch surface of the gear to be ground, mounted on said tool support, means for rotating the grinding wheel on its axis, means for simultaneously imparting to the grinding wheel an oscillatory movement about a separate axis, means for simultaneously imparting a relative movement between said wheel and the gear support toward and from said axis of oscillation to cause the wheel to move in a path other than a circular arc across the face of the gear and means for simultaneously imparting a relative rolling motion between 'said' wheel and gear support.

- 44. In a machine for grinding 'l'ongitudi nally curved tooth gears,'a gear' support, a; tool support,- a grinding wheel mounted'on said supporffmeans for-rotating the grinding' wheel on its axis; means for 'simultaneously imparting to the grinding wheel an ostive' movement'between said wheel 'a'n'dthe ofoscillation to cause the wheel to move in a cillatory movement about a' separate axis, 1 means for simultaneouslyimparting a rela face ofthe gear, and means for simultaneously imparting a relative rolling movement between said wheel and gear support.

45. In a machine for grinding longitudinally curved tooth gears, a gear support, a tool support, a grinding wheel, having an operating portion of general crescent shape in a plane tangent to the pitch surface of the gear to be ground, mounted on said tool su port, means for rotating the grinding wheel on its axis, means for simultaneously imparting to the grinding wheel an oscillatory movement about a separate axis, and means for simultaneously imparting a relative movement between said wheel and the gear support toward and ;away from said axis of oscillation to cause the wheel to move in a path other than a circular arc across the face of the gear. 7

46. In a machine for grinding longitudinally curved tooth gears, a gear support, a tool support, a grinding wheel, having concave and convex operating surfaces adapted to operate on adjacent side tooth surfacesof the gear, mounted on said tool support, means for rotating the grinding wheel on its axis, means for simultaneously imparting to the grinding wheel an oscillatory movement about a separate axis, means for imparting a relative movement between said wheel and the gear support toward and away from the axis of oscillation of said wheel to cause the wheel to move in a path other than a circular arc across the face of the gear, and means for imparting a relative rolling motion between said wheel and gear support.

47. In a gear grinding machine, a gear support, a tool support, a rotatable grinding wheel mounted on said tool support, a motor drive for imparting to said grinding Wheel its rotary motion, means for oscillating said grinding wheel to cause it to travel bodily in a longitudinally curved path across the face of the gear to be ground and a separate motor drive for actuating said oscillating means.

48. In a gear grigding machine, a gear support, a tool support, a rotatable grinding wheel mountedon said tool support, a motor drive for imparting to said grinding wheel its rotary movement, means for simultaneously lmpartmg to said grinding wheel an os-- cillatory motion, to cause said Wheel to .travel bodily in a longitudinally curved path across the face of the gear to be ground, a separate motor drive for actuating said oscillating means, means for imparting a relative rolling motion between said wheel and the gear support, and a separate motor drive for actuating said last named means.

49. In a machine for grinding longitudinally curved tooth gears, a gear support, a tool support, a rotatable grinding wheel mounted on said tool support, a drive shaft,

means for imparting rotary motion from. said drive shaft'to said grinding wheel, and means for simultaneously oscillating said tool'support about the axis of said drive shaft to cause said wheel to travel bodily in a longitudinally curved path across the face of the gear to be ground.

50. In a machine for grinding longitudinally curved tooth gears, a blank support, a dished grinding wheel, having active grinding surfaces which are portions of the inside and outside surfaces of the wheel, means for positioning said wheel so that its axisis inclinedat an acute angle to a plane tangent to the pitch surface of the gear to be ground,

means for rotating the grinding wheel on its axis and means for simultaneously moving the wheel bodily in a longitudinally curved path across the face of the gear to be ground.

51. In a machine for grinding longitudis nally curved tooth gears, a blank support, a

grinding wheel, having an operating portion of general crescent shape in a plane tangent to the pitch surface of the gear to be ground, means for rotating the grinding wheel on its axis, means for simultaneouslymoving the wheel bodily in a longitudinally curved path across the face of the gear to be ground, and means for simultaneously imparting a relative rolling motion between said wheel and gear.

52. In a machine for grinding longitudinally curved tooth gears, a blank supporu a grinding tool, having an operating portion of general crescent shape in a plane tangent to the pitch surface of the gear to be ground,

and means for reciprocating said grinding tool in a longitudinally curved path across the face of the gear to be ground.

53. In a machine for grinding longitudinally curved tooth. gears, a blank support, a grinding tool, having an operating portion of general crescent shape in a plane tangent to the pitch surface of the gear to be ground, means for reciprocating said grinding tool in a longitudinally curved path across the face of the gear to be ground, and means for simultaneously imparting a relative rolling motion betweemsaid tool and gear.

nally curved tooth gears, a blank support, a grinding tool, having an operating portion of general crescent shape in a plane tangent to the'pitch surface of the gear to be ground,

and means for moving said grinding tool in alongitudinally curved path across the face of the gear to be ground.

55. In a machine for grinding longitudimeans for simultaneously imparting an addi- 1 54. In a machine for grinding longitudi-l 115.

tional relative movement between the grinding tool and gear for grinding the tooth profiles.

56. In a machine for grinding longitudinally curved tooth gears, a blank support, a grinding tool, having an operating portion of general crescent shape in a plane tangent to the pitch surface of the gear to be ground,

an oscillatory tool carrier, upon which said tool is mounted, and means for oscillating said tool carrier to move the tool in a longitudinally curved path across the face of the gear to be ground.

57. In a machine for grinding longitudinally curved tooth gears, a blank support, a grinding tool, having an operating portion of general crescent shape in a plane tangent to the pitch surface of the gear to be ground, an oscillatory tool carrier upon which said tool is mounted, means for oscillating said tool carrier to move the tool in a longitudinally curved path across the face of the gear to be ground and means for simultaneously imparting an additional relative movement between the tool carrier and blank sup-port for grinding the tooth profiles.

58. In a machine for grinding longitudinally curved tooth gears, a blank support, an oscillatable wheel'support, a dished grinding wheel, having active grinding surfaces which are portions of the inside and outside surfaces of said wheel, journaled in said Wheel support, means for rotating the wheel on its axis, and means for simultaneously oscillating the wheel support to move the grinding wheel in a longitudinally curved path across the face of the gear.

59. In a machinefor grinding longitudinally curved tooth gears, a blank support, an oscillatable wheel support, a dished grinding wheel having active grinding surfaces which are portions of the inside and outside surfaces of the wheel, journaled in said wheel support, means for rotating the grinding wheel on its axis, means for simultaneously oscillating the wheel support to move the grinding wheel in a longitudinally curved path across the face of the gear to be ground and means for simultaneously imparting an additional relative movement between the wheel support and blank support for grinding the tooth profiles.

60. In a machine for grinding longitudinally curved tooth gears, a blank support, a dished grinding wheel, means for positioning said wheel so that its axis passes through the point about which the tooth surface of the gear to be ground is curved, means for rotating. said wheel on its axis, means for simultaneously oscillating said wheel about said point of curvature, and means for simultaneously imparting a relative rolling motion between said wheel and gear.

61. In a machine for grinding longitudinally curved tooth gears, a blank support, a

grinding wheel, having conical grinding surfaces whose apexes lie on the same side of a plane perpendicular to the axis of the wheel at its tip, means for rotating said grinding wheel on its axis, and means for simultaneously reciprocating said wheel bodily in a longitudinally curved path across the face of the gears to be ground.

62. In a machinevfor grinding longitudinally curved tooth gears, a grinding wheel, having conical grinding surfaces whose apexes lie on the same side of a plane perpendicular to the axis of the wheel at its tip, means for rotating said wheel on its axis, means for simultaneously reciprocating said wheel bodily in a longitudinally curved path across the face of the gear to be ground, and means for simultaneously imparting a relative rolling motion between said wheel and gear.

63. The method of grinding longitudinally curved tooth gears, which consists in employing a dished grinding wheel, whose operating side surfaces are of general crescent shape in a plane tangent to the pitch surface of the gear to be ground, positioning said wheel so that the centers about which the operating side surfaces of said wheel are curved in said tangent plane are at the same relative distance from the center about which two adjacent side tooth surfaces of the gear are curved, as the normals to the operating side surfaces of said wheel are from said center of curvature, rotating said wheel on its axis and simultaneously reciprocating said wheel bodily in a longitudinally curved path across the face of the gear to be ground.

HERBERT EDGAR TAYLOR. 

